1. Field of the Invention
The present invention generally relates to computer memory technology and, more particularly, to a data addressable memory architecture and a method of forming a data addressable memory.
2. Description of the Prior Art
One conventional memory architecture which is widely employed in computers is random access memory (RAM). RAM architecture functions to store data at different locations in memory which are identified by different addresses. Data can be written into RAM and read from RAM at the locations identified by the addresses. A word of stored data can only be read by using the address of its location in RAM. Thus, the address of the data's location must be known in order to access the data. Upon receipt of the address, RAM will output the data stored at that specific address, and only that data.
In conventional RAM architecture, the data stored at different addresses have no logical connection (e.g. association or relation) with the specific address. In a growing number of different applications, for instance pattern recognition and machine vision to name just a few, conventional RAM architecture performs data searching and matching operations much too slowly to be useful. If one desires to match external data representing a pattern with data stored in RAM at unknown addresses, comparisons must be made by accessing each memory address of the RAM sequentially.
Another conventional memory architecture, referred to as content addressable memory (CAM). can perform these operations much faster. The CAM architecture, also called a fully-associative memory, searches for specific data located anywhere in memory by employing a portion of the data as the address. Unlike in RAM architecture where memory locations must be searched sequentially to find the matching stored data, in CAM architecture the entire memory is searched in parallel upon receipt of a data word. Matches are made without regard to memory location; data is addressable according to content. However, CAM architecture, compared to RAM architecture, involves higher complexity and thus higher costs which has limited its use, up to the present time, primarily to super-computers. Cost-effective computers have continued to employ lower-cost RAM architecture.
Consequently, a need still exists for a computer memory architecture which will overcome the problems and shortcomings associated with conventional RAM and CAM architectures.